diff --git a/ArduCopterMega/APM_Config.h.reference b/ArduCopterMega/APM_Config.h.reference
index 68b433b5a2..cecd7722bd 100644
--- a/ArduCopterMega/APM_Config.h.reference
+++ b/ArduCopterMega/APM_Config.h.reference
@@ -712,6 +712,21 @@
 //#define LOG_CMD             ENABLED
 //
 
+//////////////////////////////////////////////////////////////////////////////
+// RC override
+//
+// ALLOW_RC_OVERRIDE                         OPTIONAL
+//
+// This is for advanced used only!
+//
+// If you enable ALLOW_RC_OVERRIDE then a GCS will be able to
+// override RC input values using a MAVLINK_MSG_ID_RC_CHANNELS_RAW
+// message sent to APM. This allows the GCS to precisely control
+// all PWM values as seen by APM, which means it can set any switch
+// position, or set a precise control value. Do not enable unless you
+// really know what you are doing!
+//
+
 //
 // Do not remove - this is to discourage users from copying this file
 // and using it as-is rather than editing their own.
diff --git a/ArduCopterMega/GCS_Mavlink.pde b/ArduCopterMega/GCS_Mavlink.pde
index 0c9ac3ac54..9dc8b3cbf4 100644
--- a/ArduCopterMega/GCS_Mavlink.pde
+++ b/ArduCopterMega/GCS_Mavlink.pde
@@ -673,6 +673,28 @@ void GCS_MAVLINK::handleMessage(mavlink_message_t* msg)
             break;
         } // end case
 
+#if ALLOW_RC_OVERRIDE == ENABLED
+	case MAVLINK_MSG_ID_RC_CHANNELS_RAW:
+	    {
+			// allow override of RC channel values for HIL
+			// or for complete GCS control of switch position
+			// and RC PWM values.
+			mavlink_rc_channels_raw_t packet;
+			int16_t v[8];
+			mavlink_msg_rc_channels_raw_decode(msg, &packet);
+			v[0] = packet.chan1_raw;
+			v[1] = packet.chan2_raw;
+			v[2] = packet.chan3_raw;
+			v[3] = packet.chan4_raw;
+			v[4] = packet.chan5_raw;
+			v[5] = packet.chan6_raw;
+			v[6] = packet.chan7_raw;
+			v[7] = packet.chan8_raw;
+			APM_RC.setHIL(v);
+			break;
+		}
+#endif
+
 #if HIL_MODE != HIL_MODE_DISABLED
         // This is used both as a sensor and to pass the location
         // in HIL_ATTITUDE mode.
@@ -700,23 +722,6 @@ void GCS_MAVLINK::handleMessage(mavlink_message_t* msg)
             break;
         }
 
-	case MAVLINK_MSG_ID_RC_CHANNELS_RAW:
-	    {
-			// allow override of RC channel values for HIL
-			mavlink_rc_channels_raw_t packet;
-			int16_t v[8];
-			mavlink_msg_rc_channels_raw_decode(msg, &packet);
-			v[0] = packet.chan1_raw;
-			v[1] = packet.chan2_raw;
-			v[2] = packet.chan3_raw;
-			v[3] = packet.chan4_raw;
-			v[4] = packet.chan5_raw;
-			v[5] = packet.chan6_raw;
-			v[6] = packet.chan7_raw;
-			v[7] = packet.chan8_raw;
-			APM_RC.setHIL(v);
-			break;
-		}
 #endif
 #if HIL_MODE == HIL_MODE_ATTITUDE
     case MAVLINK_MSG_ID_ATTITUDE:
diff --git a/ArduCopterMega/config.h b/ArduCopterMega/config.h
index 0342f8052e..d78d1bb412 100644
--- a/ArduCopterMega/config.h
+++ b/ArduCopterMega/config.h
@@ -550,3 +550,11 @@
 #define STANDARD_SPEED_SQUARED (STANDARD_SPEED * STANDARD_SPEED)
 #endif
 #define STANDARD_THROTTLE_SQUARED (THROTTLE_CRUISE * THROTTLE_CRUISE)
+
+
+//////////////////////////////////////////////////////////////////////////////
+// RC override
+//
+#ifndef ALLOW_RC_OVERRIDE
+# define ALLOW_RC_OVERRIDE DISABLED
+#endif